Homogeneous, epitaxial buried layers of 3C-SiC have been formed in Si(100) and Si(111) by ion beam synthesis (IBS) using 180 keV high dose C ion implantation. It is shown that an annealing temperature of 1,250 C and annealing times of 5 to 10 h are sufficient to achieve well-defined Si/SiC/Si layer systems with abrupt interfaces. The influence of dose, annealing time and temperature on the layer formation is studied. The favorable dose is observed to be dependent on the substrate orientation. IBS using 0.8 MeV C ions resulted in a buried SiC precipitate layer of variable composition.

Well-defined, homogeneous, deep-buried 3C-SiC layers have been formed in silicon by ion beam synthesis using MeV C{sup +} ions. Layers are characterized by RBS/channeling, X-ray diffraction, x-sectional TEM and electron diffraction. The redistribution of implanted carbon atoms into a rectangular carbon depth distribution associated with a well-defined layer during the post-implantation anneal is shown to depend strongly on the existence of crystalline carbide precipitates in the as-implanted state.

Doped buried layers formed by MeV ion implantation are attractive alternatives to expensive epitaxial substrates for controlling latch-up in CMOS devices. Two different process architecture approaches for forming effective buried layers are discussed. P+ Around Boundary (PAB), and a more recent derivative, BILLI are compared to a Buried Layer/Connecting Layer (BUCL) architecture, with regards to latch-up resistance, process flexibility, and future scalability. While both architectures have been shown to increase latch-up trigger current on bulk silicon, the BUCL process provides greater latch-up control and process/device flexibility. Process and device simulations as well as experimental data indicate that a properly chosenmore » set of implants for both n-well, p-well, and buried layer structures can yield latch-up isolation superior to 3mm epi.« less

Buried recombination layers were formed in silicon by high energy implantation of carbon or oxygen and subsequent annealing. The parasitic lateral bipolar transistors in latch-up test structures with these buried recombination layers showed a strong decrease of the current gain by 2 to 3 orders of magnitude in n-type silicon and by 4 - 5 decades in p-type silicon. Reduction of lateral minority carrier diffusion was tested by injecting minority carriers in the vicinity of a reverse biased well recording the resulting reverse currents. The distance between well and injecting contact was varied between 10 and 50 {mu}m. The carbonmore » implanted layer reduced the reverse current by up to 6 orders of magnitude while the oxygen implanted layer reduced the current by up to 3 orders of magnitude.« less

Gravimetric techniques offer a convenient and accurate method of determining surface layer porosity in both n- and p-type porous silicon (PS). Porosity of the PS affects its volume expansion on oxidation and the insulating properties of the resulting oxide. Optimal porosity (ca. 55%) yields fully dense, insulating oxides with minimal expansion-induced stresses. Two factors affect the porosity: chemical dissolution of PS by the anodization electrolyte, and oxidation of the PS to produce a native oxide on the surface. Buried layer porosities cannot normally be measured by gravimetric techniques unless the volume of the buried layer is large enough to yieldmore » a measurable weight change on anodization. We therefore used a form of Faraday's Law to determine buried layer porosities and determined that they can be correlated with porosities of surface layers formed under identical conditions. 9 refs., 4 figs.« less